Drug offers hope in war on prostate cancer

When a doctor diagnosed Carl Raba with prostate cancer nine years ago, he said, “it was like hitting a brick wall.”

Raba, 75, of San Antonio, said he didn't know whether to undergo radiation treatment or surgery until Dr. Ian Thompson, director of the Cancer Therapy & Research Center at the University of Texas Health Science Center at San Antonio, told him of a third option — observe the cancer over time and join a research study.

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A new study, led by Thompson and published Wednesday in the New England Journal of Medicine, found that finasteride reduces prostate cancer risks by 30 percent.

The research builds upon a previous study, also led by Thompson, and may tone down fears about the drug with findings that it doesn't affect the survival rates of men taking it.

“By taking this medication, your cure rate appeared to be the same, but you find fewer cancers,” Thompson said. “That's a good thing.”

The results stem from the Prostate Cancer Prevention Trial which started in 1993. It was funded by a National Cancer Institute grant and enrolled almost 19,000 men, about 2,000 of them from San Antonio, he said.

In the original study, published in 2003, researchers paradoxically found that while the drug reduced the risk of prostate cancers by 25 percent, they also identified more aggressive prostate cancers in men taking finasteride, Thompson said.

Other research since has concluded that doctors found the aggressive cancers because the drug makes blood tests, prostate exams and biopsies more sensitive to the detection of cancer, he said.

“Because of that concern, even though the study met its objective — reduced the risk of prostate cancer by a quarter — people said maybe we shouldn't give the medication to prevent prostate cancer,” he said.

Cancer of the prostate, a gland that is part of the male reproductive system, is the most common cancer in men, according to the Centers for Disease Control and Prevention. Nearly 240,000 men in the United States will develop prostate cancer and about 30,000 will die of it this year, according to National Cancer Institute estimates.

“It reduces the bad hormone in the prostate,” Thompson said of the drug physicians prescribe to treat enlarged prostates and hair loss in men. “In a man who has prostate enlargement ... it shrinks the prostate, helps urinary symptoms and helps prevent problems over time.”

Finasteride's other side effects also include breast tenderness and a reduction in libido and erections, he said.

Thompson and other researchers analyzed the death records of those in the study through 2011, the same year the U.S. Food and Drug Administration added a warning that finasteride “may increase the risk of high-grade prostate cancer.”

“If these aggressive cancers were more common with finasteride, you would expect more deaths in those that take finasteride,” Thompson said, but his new study found that the survival rates “were exactly the same.”

The new study also found that finasteride reduces prostate cancer risks by 30 percent, instead of the initially reported 25 percent, Thompson said.

In more tangible terms, 30 percent of those expected to be diagnosed with prostate cancer this year would equate to more than 71,000 men.

“From a public health standpoint, it's enormous,” he said, adding that he had no personal investment in the drug.

Though Raba may not have been a participant in this particular finasteride study, he advocates for using the drug if it can help other men and their families avoid the anxiety and costs of fighting slow-growing cancer like his.